1. Field of the Invention
The present invention relates to a laser control circuit for controlling the output wavelength of a laser diode and to a laser module including the laser control circuit.
2. Related Background Art
A laser module is an optical device including a laser diode. The laser module is used, for example, as a light source for an optical communication system.
In a WDM communication system, the output wavelengths of the laser modules must be fixed. This is done to distinguish the communication channels from each other. In the WDM communication system, a plurality of communication channels with different wavelengths are used at the same time. The laser modules are used as light sources for such communication channels. Each communication channel is allocated to each wavelength band. Therefore, it is necessary to fix the output wavelengths of the laser modules in order to distinguish the channels by the wavelengths.
A wavelength monitor is sometimes disposed in the laser module to monitor the output wavelength. Such monitoring makes it possible to check whether the light with an appropriate wavelength is emitted.